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Dr Yvonne Couch

Extracellular Vesicles and Stroke: The Hunt for Tiny Messengers

"When you have a stroke, your whole body knows about it, not just your brain. But the thing is, we don’t really know how this happens. If you decide to wave at a person you know across the street, your brain sends signals via your nerves to your hand and arm muscles to tell them to wave. Similarly if you step on a pin, your foot sends signals via nerves to your brain to tell it that pain is happening. But if your brain is injured, the signals that escape don’t go via the nerves, they use other routes. One of these routes might be using things called extracellular vesicles as tiny messengers.

"Extracellular vesicles (EVs), are little fragments of cell membrane that look like tiny bubbles. These are between one tenth, and one one-hundredth the size of a single cell. They can come from the surface of the cell, or they can come from within the cell. Until around 10 years ago, these vesicles were thought of as debris. Junk that cells made but that didn’t do anything. Now we know that these act as messengers between cells, conveying key information.

"My work aims to find out whether these vesicles are involved in what happens to your body after you have a stroke. One of the major events post-stroke is activation of the immune system, both in the brain, and in the rest of the body. This can have serious consequences and even make the outcome of the stroke worse. My theory is that extracellular vesicles are released from the brain and contain information that causes the immune system to become activated. How they do this, whether they can be stopped, or even if we need to stop them, remains to be discovered. The hunt for tiny messengers continues. Watch this space!"